Bias control device and method suitable for dual-polarization IQ modulator

Abstract

The invention discloses a bias control device and method suitable for a dual-polarization IQ modulator, and relates to the field of optical signal modulation. The bias control device comprises an optical coupler, a photoelectric detector, an ADC and an FPGA chip, wherein the optical coupler, the photoelectric detector, the ADC and the FPGA chip are connected in sequence, and the FPGA chip is respectively connected with a first DAC, a second DAC, a third DAC, a fourth DAC, a fifth DAC and a sixth DAC, and controls the bias of the modulator through the DAC. The method comprises the steps of determining the initial value of an IQ bias voltage by minimizing the output optical power of the modulator, respectively overlapping low-frequency low-amplitude dither signals on the IQ bias voltage, and achieving the accurate control over the IQ bias voltage and a phase difference bias voltage through an iterative algorithm.

Description

technical field [0001] The invention relates to the field of optical signal modulation, in particular to a bias voltage control device and method suitable for a dual-polarization IQ modulator. Background technique [0002] At present, optical communication is developing towards higher speed and higher capacity. In high-speed optical transmitters, the modulation of optical signals usually requires the use of dual MZM (Mach-Zehnder Modulator)-based Polarized IQ (In-phase Quadrature) modulator. However, the optical IQ modulator itself is easily affected by some environmental factors such as temperature, etc., which will cause its static operating point to shift and degrade the system performance. In order to ensure the stability of the signal quality without affecting the system performance, it is necessary to monitor and control the bias voltage of the two polarization arms of the IQ modulator at the same time, so that both polarization arms work at the best static operating ...

AI Technical Summary

Problems solved by technology

However, research on bias voltage control suitable for OFDM (Orthogonal Frequency Division Multiplexing) systems is still relatively small, and there is almost no research on dual polarization modulators.

In theory, the bias voltage can be controlled by detecting the output optical signal power of the OFDM modulated signal, but in practical applications, the optical power near the optimal static operating point does not change significantly, and the impact of device noise is enough to cause the operating point to deviate from the optimum. good points, leading to system performance degradation

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